Over two decades ago, Dr. Harry Shirkey coined the term "therapeutic orphan" to emphasize the dearth of scientific knowledge in pediatric therapeutics. Despite advancements which have dramatically increased the knowledge base in Pediatric Clinical Pharmacology, a survey of the 1991 PDR found that 62% of all FDA-approved drugs listed did not contain pediatric dosage recommendations or alternatively, were not recommended for use in children. This demonstrates that our "new knowledge" has done little to improve the approval process for drugs in infants and children. Nevertheless, we continue to expand the use of drugs in pediatric patients without the necessary and rigorous approach demanded by society for the development of drugs in adults. This dilemma is perpetuated b y: 1) an absence of a "consortium" for pediatric pharmacology capable of working with the FDA and pharmaceutical manufacturers for pediatric drug development, 2) a regulatory mandate regarding the importance of pediatric drug research and 3) a societal "misperception" that investigation in Pediatric Clinical Pharmacology is too difficult, too costly (i.e., insufficient return on investment) or places children at an unacceptable level of risk. Clearly, these problems are not insurmountable and must be rectified if we are to remove the stigma of the "therapeutic orphan". A demonstrable step solving many of these problems resides with the establishment of the Pediatric Pharmacology Research Unit (PPRU) Network. Since 1988, the Section on Pediatric Clinical Pharmacology at the Arkansas Children's Hospital (ACH) has actively and aggressively pursued the main goal of the PPRU Network; namely, "to increase the number and variety of medications that are FDA-approved for use in children, with the ultimate goal that all drugs prescribed for children be labeled for such use". This has been accomplished by the assembly of a state-of-the-art core laboratory facility, a Pediatric Clinical Research Unit and a group of professionals (3 MDs, 1 PhD, 2 PharmDs, 1 RN and 2 Research Associates) with formal training and/or experience in Clinical Pharmacology who have emphasized the investigation of both old and new drugs in neonates, infants, children and adolescents. The Section on Pediatric Clinical Pharmacology at ACH currently possesses the personnel, experience, facility and organizational requirements mandated for the establishment of a PPRU. Accordingly, this Unit is ideally suited to fully address the specific aims of the program: 1) to enable a locus for the pre- and post-marketing clinical evaluation of drugs for children in cooperation with industry, 2) to propose independent investigator initiated studies (i.e., clinical pharmacology of antihypertensive and diuretic agents in children, prospective identification and evaluation of drug toxicity/adverse drug effects), 3) to effectively participate in a network with other established Pediatric Clinical Pharmacology programs and 4) to provide an environment for collaborative training in Pediatric Clinical Pharmacology to increase the number of qualified investigators in this area. This will be accomplished by the organization of a PPRU at ACH which will be facilitated and sustained by this grant award. The research completed by this Unit and the PPRU Network over the next five years will form the framework necessary to elevate pediatric patients in the drug development process to a first priority status.